water hammer - ca-nv-awwa.orgca-nv-awwa.org/.../session1pipelinerehabilitation/waterhammer.pdf ·...

Water Hammer

Jake Walsh, P.E.

Andy Yang, P.E.

October 21, 2014

Tackling Transient Events at San Jose Water Company

Introduction

• [map of SJWC]

Map data © 2014 Google

What is Water Hammer?

Water hammer events (transient events) are disturbances in water flow from one steady-state condition to another.

Introduction

What are Typical Causes of Water Hammer?

– Pump operations– Valve operations– Main breaks– Rapid demand changes (hydrant flow)

(adapted from AWWA Manual M32; Mays, Water Resources Engineering 2005 Edition)

OFF

Wave Propagation Animations

ON

Pump Start Up

Pump Shut Off

Hi

Low

Pressure Scale

ON

OFF

Hydraulic transient related concerns at SJWC:– Infrastructure damage– Property damage– Regulatory compliance– Public safety (pipe ruptures)– Public health (negative pressures)– Complaints

Hydraulic Transient Concerns at SJWC

• SJWC Goals– Verify existence and extent of problem– Determine mitigation measures

• SJWC Approach– Obtain necessary knowledge and analysis tools– Conduct field tests– Analyze data– Select surge protection devices

Transient Analysis – Goals and Approach

Background– History of problems and mitigation efforts– New booster pumps installed with pump control valves– Surge tanks installed

Transient Analysis – Vickery Pump Station

Field Testing

– Select strategic locations to install pressure loggers

• Pump discharge

• High pressure regions

• Low pressure regions

• Dead end mains

– Coordinate with Operations department

• Pump operations


Transient Analysis – Vickery Pump StationTransient Analysis – Vickery Pump StationLogger 1

Pump Discharge

Logger 2Low Pressure Service

Logger 3High Pressure Hydrant

100

110

120

130

140

150

160

170

180

190

200

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up – Pump Control Valve Setting


186 psi

116 psi

Transient Analysis – Vickery Pump Station1

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

Pre

ssu

re (

psi

)

Time (s)

Pump Shut Off – Pump Control Valve Setting


132 psi

11 psi

12 psi


10 s

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up and Shut Down – Pump Discharge


186 psi

116 psi

Transient Analysis – Vickery Pump StationTransient Analysis – Vickery Pump Station

132 psi

11 psi

1


100

110

120

130

140

150

160

170

180

190

200

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up With Surge Tank - Pump Discharge

186 psi

116 psi

160 psi


0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

Pre

ssu

re (

psi

)

Time (s)

Pump Shut Off With Surge Tank - Pump Discharge


132 psi

11 psi

88 psi


-20

-10

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up and Shut Down – Low Pressure Service


125 psi

63 psi


73 psi

-14.7 psi

2

50

60

70

80

90

100

110

120

130

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up With Surge Tank – Low Pressure Service


125 psi

63 psi

98 psi


-20

-10

0

10

20

30

40

50

60

70

80

90

Pre

ssu

re (

psi

)

Time (s)

Pump Shut Off With Surge Tank - Low Pressure Service


73 psi

-14.7 psi

38 psi


120

130

140

150

160

170

180

190

200

210

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up and Shut Down – High Pressure Hydrant


197 psi


143 psi

Static Pressure ~ 171 psi Run Pressure ~ 173 psi

3

170

175

180

185

190

195

200

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up With Surge Tank – High Pressure Hydrant


197 psi

Static Pressure 171 psi

188 psi


Record Start Trigger ~ 178 psi

Record Stop Trigger ~ 173 psi

3

120

130

140

150

160

170

180

190

Pre

ssu

re (

psi

)

Time (s)

Pump Shut Off With Surge Tank – High Pressure Hydrant


143 psi

Static Pressure 171 psi With surge tank online, transient waves remained within recording triggers


Upper Record Start Trigger ~ 178 psi

Lower Record Start Trigger ~ 161 psi

3

Background

– History of problems

– Mitigation efforts

Transient Analysis – Pavilion Pump Station

Field Testing

– Strategic locations to install pressure loggers

– Coordination with Operations department

Surge Modeling

– Calibration of existing system

– Future system (with surge protection device)


Transient Analysis – Pavilion Pump StationTransient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station

LoggerPump Discharge

Reservoir

Transmission Main Split

125

135

145

155

165

175

185

195

205

0 5 10 15 20 25 30 35

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up - Pump Discharge

Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station201 psi

145 psi

198 psi

Reflection wave from transmission main split

Reflection wave from reservoir

1

2

3

1

2

3

0

20

40

60

80

100

120

140

160

180

200

220

0 5 10 15 20 25 30 35 40

Pre

ssu

re (

psi

)

Time (s)

Pump Shut Off - Pump Discharge

Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station

156 psi

70 psi

64 psi

200 psi

186 psi186 psi 196 psi

Reflection wave from transmission main split

Reflection wave from reservoir

Initial Surge Tank Sizing:


𝑻𝒄 =𝟐𝑳

𝒂

𝑺𝒖𝒓𝒈𝒆 𝑻𝒂𝒏𝒌 𝑽𝒐𝒍𝒖𝒎𝒆 = 𝟒. 𝟓 𝒔 × 𝟖. 𝟕 𝒈𝒂𝒍/𝒔 = 𝟒𝟎 𝒈𝒂𝒍

𝑻𝒄 =𝟐 × 𝟒, 𝟎𝟖𝟎 𝒇𝒕

𝟏, 𝟖𝟎𝟎 𝒇𝒕/𝒔= 𝟒. 𝟓 𝒔

𝑺𝒖𝒓𝒈𝒆 𝑻𝒂𝒏𝒌 𝑽𝒐𝒍𝒖𝒎𝒆 = 𝑻𝒄 × 𝑸

125

135

145

155

165

175

185

195

205

0 5 10 15 20 25 30 35

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up - 50% Water / 50% Air


145 psi

200 psi

40 gal

80 gal

160 gal

265 gal

125

135

145

155

165

175

185

195

205

0 5 10 15 20 25 30 35

Pre

ssu

re (

psi

)

Time (s)

Pump Start Up - 35% Water / 65% Air


145 psi

200 psi

40 gal80 gal

160 gal

265 gal

0

20

40

60

80

100

120

140

160

180

200

220

240

260

0 5 10 15 20 25 30 35 40

Pre

ssu

re (

psi

)

Time (s)

Pump Trip - 2 Pumps 50% Water / 50% Air


236 psi

40 gal

80 gal

160 gal265 gal

15 psi

0

20

40

60

80

100

120

140

160

180

200

220

240

260

0 5 10 15 20 25 30 35 40

Pre

ssu

re (

psi

)

Time (s)

Pump Trip - 2 Pumps 35% Water / 65% Air


236 psi

80 gal

160 gal

265 gal

15 psi

• Hydraulic transients are regularly occurring in water distribution systems

• Transient waves can be far more extreme than anticipated

• Transient waves propagate further than expected

• Certain surge protection devices can be very effective, others not as effective

• Surge protection devices can help mitigate potential public safety and public health concerns

• Surge modeling is highly recommended for sizing surge protection devices

• More transient analysis needs to be performed

Conclusion

Jake Walsh, P.E.

Engineering Unit Manager

[email protected]

Andy Yang, P.E.

Associate Engineer

[email protected]

Contact Information

water hammer - ca-nv-awwa.orgca-nv-awwa.org/.../session1pipelinerehabilitation/waterhammer.pdf ·...

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